Method and apparatus for lightweight multilingual natural language realizer

ABSTRACT

Methods, apparatuses, and computer program products are described herein that are configured to be embodied as a natural language realizer in the form of a lightweight multilingual realizer. In some example embodiments, a method is provided that comprises generating syntactically correct natural language. The method of this embodiment may also include at a syntax processor, propagating features among a group of words, and adding closed class function words and morphological inflections.

TECHNOLOGICAL FIELD

Embodiments of the present invention relate generally to natural language generation technologies and, more particularly, relate to a method, apparatus, and computer program product for lightweight multilingual natural language realization.

BACKGROUND

In some examples, a natural language generation (NLG) system is configured to transform raw input data that is expressed in a non-linguistic format into a format that can be expressed linguistically, such as through the use of natural language. For example, raw input data may take the form of a value of a stock market index over time and, as such, the raw input data may include data that is suggestive of a time, a duration, a value and/or the like. Therefore, an NLG system may be configured to input the raw input data and output text that linguistically describes the value of the stock market index; for example, “Securities markets rose steadily through most of the morning, before sliding downhill late in the day.”

Data that is input into a NLG system may be provided in, for example, a recurrent formal structure. The recurrent formal structure may comprise a plurality of individual fields and defined relationships between the plurality of individual fields. For example, the input data may be contained in a spreadsheet or database, presented in a tabulated log message or other defined structure, encoded in a ‘knowledge representation’ such as the resource description framework (RDF) triples that make up the Semantic Web and/or the like. In some examples, the data may include numerical content, symbolic content or the like. Symbolic content may include, but is not limited to, alphanumeric and other non-numeric character sequences in any character encoding, used to represent arbitrary elements of information. In some examples, the output of the NLG system is text in a natural language (e.g. English, Japanese or Swahili), but may also be in the form of synthesized speech.

BRIEF SUMMARY

Methods, apparatuses, and computer program products are described herein that are configured to be embodied as and/or performed by a lightweight multilingual natural language realizer. In one example embodiment, a method comprises accessing a realization element data structure, wherein the realization element data structure is a syntactic representation of phrases and sentences; and accessing at least one syntax rule file at a syntax processor in a natural language realizer, wherein the at least one syntax rule file is configured for a language. The method of this embodiment may also include generating a syntactically processed realization element data structure, at the syntax processor, using the at least one syntax rule file in the syntax processor. The method of this embodiment may further include generating a syntactically processed realization element data structure by: propagating features in the realization element data structure by comparing one or more realization elements in the realization element data structure; and adding closed class function words and morphological inflections by utilizing rules from the language syntax rule file to determine closed class function words and morphological inflections to add to the base words and phrases in the realization element data structure.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 is a schematic representation of natural language generation environment that may benefit from some example embodiments of the present invention;

FIG. 2 illustrates an example configurable lightweight multilingual realizer according to some example embodiments described herein;

FIG. 3 illustrates an example syntax processor according to some example embodiments described herein;

FIG. 4 illustrates a block diagram of an apparatus that embodies a lightweight multilingual realizer system in accordance with some example embodiments of the present invention; and

FIGS. 5 and 6 illustrate flowcharts that may be performed by a lightweight multilingual natural language realizer in accordance with some example embodiments of the present invention.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the embodiments may take many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. The terms “data,” “content,” “information,” and similar terms may be used interchangeably, according to some example embodiments, to refer to data capable of being transmitted, received, operated on, and/or stored. Moreover, the term “exemplary”, as may be used herein, is not provided to convey any qualitative assessment, but instead merely to convey an illustration of an example. Thus, use of any such terms should not be taken to limit the spirit and scope of embodiments of the present invention.

In some examples, the stage of natural language generation known as sentence planning and/or microplanning includes the process of transforming, mapping or otherwise converting fragments of data, information or the like (e.g. messages) into specifications (e.g. phrase specifications, sentence plans or the like), such that the specifications can be further processed by a realizer (e.g. a linguistic realization component). In some examples, the stage of natural language generation known as realization includes the process of mapping such a specification, and its constituent phrase specifications (referred to hereinafter as “realization elements”), into surface text. Surface text, in some examples, includes words, punctuation symbols, and mark-up annotation.

In some examples, the example microplanner disclosed herein is configured to generate text specifications for a given language wherein the base words and phrases are mostly ordered into a syntactic representation of phrases and sentences. In some examples, a realizer is then able to more simply and efficiently process realization elements in the text specification, so as to be able to transform the language specific realization elements into surface text in the given language.

In some examples, the ability for the example lightweight multilingual realizer to receive ordered words allows for the realizer to forego the traditional rules and process of re-ordering words, leading to not only a lightweight nature for the realizer, but also leading to the ability to advantageously add support for multiple languages. That is, given the design described herein, adding a language to the lightweight multilingual realizer comprises constructing feature propagation rules for the language to be added to the realizer, and writing rules for adding closed class function words and morphological inflections.

For example, adding a language, such as Portuguese, to a lightweight multilingual realizer, which may include a previously implemented language such as English, may consist of first writing a set of feature rules describing how features propagate in Portuguese. Feature propagation in Portuguese may include variations that are different from the English rules in the multilingual processor. These variations can include gendered words and phrases found in Portuguese, but not English. Adding Portuguese will also consist of writing rules for adding closed class function words and morphological inflections. The rules can then be implemented by the lightweight multilingual realizer and allow for the realizer to accept realization elements from the microplanner in either English or Portuguese.

In some embodiments, the lightweight multilingual nature of the realizer described herein allows for more maintainable code and more correct natural language generation, even as multiple new languages utilize the realizer. That is, the realizer itself is also more flexible as it allows for ease of adding or modifying languages, or dialects of languages. Importantly, the systems and methods below provide separate processing modules for propagating features, and adding closed class function words and morphological inflections. That is, each of the modules are configured to operate independently of one another. Such independence allows for the modules to be modifiable to account for languages with distinct syntax and grammar structures.

Additionally, the systems and methods described herein provide a robust realization component that allows for a generic parent class that presents an application programming interface that allows for language specific implementations with each language having its own specific rule files for operation. Specifically, a realization element is processed, in some examples, so as to propagate features, add closed-class function words, such as the insertion of conjunctions (and, or), articles (a, the), demonstratives (this, that) and prepositions (to, from, at, with), and add morphological inflections. Closed-class function words may also include “not”, “will”, and auxiliary verbs.

In some embodiments, realization elements can be received into the realizer from sources other than the microplanner, such as a document planner or a template. In some examples, a realizer may be called from a template via lightweight NLG services. For example, a template may specify the verb EAT and the features negated:true, progressive:true, and invoke the realizer, via a lightweight NLG service (without invoking a document planner and/or microplanner), to produce the string “is not eating”, which is subsequently inserted into the template by the realizer.

FIG. 1 is an example block diagram of example components of an example natural language generation environment 100. In some example embodiments, the natural language generation environment 100 comprises a natural language generation system 108, input data 110, and a data analysis system 104. The natural language generation system 108 may take the form of, for example, a code module, a component, circuitry and/or the like. The components of the natural language generation environment 100 are configured to provide various logic (e.g. code, instructions, functions, routines and/or the like) and/or services related to the lightweight multilingual natural language realizer.

The data analysis system 104 is configured to store generated messages that are sent to the natural language generation system 108. Messages are language independent data structures that correspond to informational elements in a text and/or collect together underlying data, referred to as slots, arguments or features, which can be presented within a fragment of natural language such as a phrase or sentence. Messages may be represented in various ways; for example, each slot may consist of a named attribute and its corresponding value; these values may recursively consist of sets of named attributes and their values, and each message may belong to one of a set of predefined types. The concepts and relationships that make up messages may be drawn from an ontology that formally represents knowledge about the application scenario.

In some examples, messages are created based on a requirements analysis as to what is to be communicated for a particular scenario (e.g. for a particular domain or genre). A message typically corresponds to a fact about the underlying data (for example, the existence of some observed event) that could be expressed via a simple sentence (although it will ultimately be realized by some other linguistic means). For example, to linguistically describe wind, a user may want to know a speed, a direction, a time period or the like, but the user may also want to know changes in speed over time, warm or cold fronts, geographic areas and or the like. In some cases, users do not even want to know wind speed values, but instead want an indication that describes the presence of a dangerous wind condition. Thus, a message related to wind speed may include fields to be populated by data related to the speed, direction, time period or the like, and may have other fields related to different time points, front information or the like. The mere fact that wind exists may be found in the data, but to linguistically describe “light wind” or “gusts” different data interpretation must be undertaken as is described herein.

In some examples, a message is created in an instance in which the raw input data warrants the construction of such a message. For example, a wind message would only be constructed in an instance in which wind data was present in the raw input data. Alternatively or additionally, while messages may correspond directly to observations taken from a raw data input, others may be derived from the observations by means of a process of inference or based on one or more detected events. For example, the presence of rain may be indicative of other conditions, such as the potential for snow at some temperatures.

Messages may be instantiated based on many variations of source data, such as but not limited to time series data, time and space data, data from multiple data channels, an ontology, sentence or phrase extraction from one or more texts, a text, survey responses, structured data, unstructured data and/or the like. For example, in some cases, messages may be generated based on text related to multiple news articles focused on the same or similar news stories in order to generate a news story; whereas in other examples, messages may be built based on survey responses and/or event data.

Messages may be annotated with an indication of their relative importance; this information can be used in subsequent processing steps or by the natural language generation system 108 to make decisions about which information may be conveyed and which information may be suppressed. Alternatively or additionally, messages may include information on relationships between the one or more messages.

In some examples, one or more messages may be built based on raw input data, such as the time-series data in the following table:

Heart Respiration Time Rate Rate 1 68 14 2 72 15 3 70 14 4 70 14 5 69 16 6 72 15 7 73 16 8 68 13 9 70 14 10 71 15 11 90 14 12 110 14 13 118 14 14 116 15 15 105 15 16 92 14 17 86 13 18 80 14 19 75 14 20 72 15 21 70 14 22 71 13 23 69 13 24 71 14

Using the heart rate data channel in the above table as an example, a message may include a patient or reference name, a period, a change in heart rate, a starting heart rate, a high heart rate and an ending heart rate.

In some example embodiments, a natural language generation system, such as natural language generation system 108, is configured to generate phrases, sentences, text or the like which may take the form of natural language text. The natural language generation system 108 comprises a document planner 130, a microplanner 132 and/or a natural language realizer such as lightweight multilingual realizer 134. The natural language generation system 108 may also be in data communication with a multilingual rules file 140 and a multilingual lexicon 142.

In some examples, the multilingual rules 140, used in conjunction with the multilingual lexicon include, but are not limited to, a plurality of language rule files, each of the plurality of language rule files including a syntax rule file, which in some examples includes rules to add closed class function words and morphological inflections, and propagate features. In some examples, the plurality of languages rule files may also include a morphology rule file, a morphophonology rule file, an orthography rule file, and/or a mark-up rule file, which may be used by the document planner 130, the microplanner 132 and/or the lightweight multilingual realizer 134. The multilingual rules 140 are further described with respect to FIG. 2. Other natural language generation systems may be used in some example embodiments, such as a natural language generation system as described in Building Natural Language Generation Systems by Ehud Reiter and Robert Dale, Cambridge University Press (2000), which is incorporated by reference in its entirety herein.

A lexicon is a “dictionary” for stored words of a particular language. It identifies the part of speech and other information about words. A lexicon may also include information concerning morphological inflections, syntactic features (such as transitive verbs), whether to include “a” or “an” before a given word, and spelling variants of a single word (such as “colour” and “color”). Accordingly, multilingual lexicon 142, may comprise a single lexicon for a single language, and/or multiple lexicons that in turn support one or more languages.

The document planner 130 is configured to input the one or more messages from the data analysis system 104. The document planner 130 is further configured to determine how to arrange those messages in order to describe the patterns in the one or more data channels derived from the raw input data. The document planner 130 may comprise a content determination process that is configured to select the messages, such as the messages that contain a representation of the data that is to be output via a natural language text.

The document planner 130 may also comprise a structuring process that determines the order of messages to be included in a text. In some example embodiments, the document planner 130 may access one or more text schemas for the purposes of content determination and document structuring. A text schema is a rule set that defines the order in which a number of messages are to be presented in a document. For example, an event message (e.g. medication injection) may be described prior to a key event message (e.g. rise in heart rate). In other examples, a significant event message (e.g. falling pulse) may be described after, but in relation to, a key event message (e.g. rise in heart rate).

The output of the document planner 130 may be a tree-structured object or other data structure that is referred to as a document plan. In an instance in which a tree-structured object is chosen for the document plan, the leaf nodes of the tree may contain the messages, and the intermediate nodes of the tree structure object may be configured to indicate how the subordinate nodes are related (e.g. elaboration, consequence, contrast, sequence and/or the like) to each other, specify document structure (e.g. paragraph breaks) and/or the like.

The microplanner 132 generates a realization element data structure. The realization element data structure is then output by the microplanner 132 to the lightweight multilingual realizer 134, to express the text specification in natural language. The realization process is further described with regard to FIGS. 2, 3, 5, and 6. The output of the process is, in some example embodiments, a well-formed natural language text that takes the form, in some examples, of a sentence in a designated language. In some examples, the natural language text may include embedded mark-up.

FIG. 2 is an example block diagram of example components of an example lightweight multilingual realizer 134 in operation with a multilingual rules file 140 and multilingual lexicon 142. The multilingual lexicon 142, in some examples, is a vocabulary or language from a plurality of languages and enables the inclusion of multiple language specific lexicons such as lexicons 242 a, 242 b, and 242 c. In some embodiments, each of the lexicons 242 a, 242 b, 242 c, represent vocabularies of different languages such as English, German, and French respectively. In some embodiments, the syntax processor 210, the morphology processor 212, and the morphophonology processor 214 are configured to query the multilingual lexicon 142 and the language specific lexicons 242 a, 242 b, and 242 c.

The multilingual rules file 140 include at least one language rules file such as 240 a, 240 b, and 240 c. In some embodiments, each of the language rules files 240 a, 240 b, and 240 c represent realization rules of different languages such as English, German, and French. Each of these files may include rules for each of several realization operations such as syntax operations, morphology operations, morphophonology operations, orthography operations, and mark-up operations. Each of these rule files is configured, in some examples, to be accessed, read, and the rules implemented by one or more of the syntax, morphology, morphophonology, orthography, or mark-up processors. This process for syntax operations, within realizer 210, is further described with respect to FIGS. 3, 5, and 6. This process for morphology operations, morphophonology operations, orthography operations, and mark-up operations is described below.

The language rules file 240 a, 240 b, and 240 c may also be configured to include rules for other syntax operations described in FIG. 3. The language rules files 240 a, 240 b, and 240 c may also be similarly configured to optionally include rules for morphology, morphophonology, orthography, and mark-up operations according to the language of the rule file. Wherein each of the language rules files also includes rules for the realizer processors as described below.

The lightweight multilingual realizer 134, in some examples, may include processors to complete realization operations including a syntax processor 210, a morphology processor 212, a morphophonology processor 214, an orthography processor 216, and a mark-up processor 218. In operation, the lightweight multilingual realizer 134 is configured to receive and access realization elements, such as realization element data structure 230, including a syntactic representation of phrases and sentences and output natural language text 250, which represents the realization elements in well-formed and realized natural language text. In some examples, all of the processors to complete realization operations are optional. In some examples, the morphophonology processor 214, the orthography processor 215, and the mark-up processor are all optional. For example, a realization element data structure 230 may not need to be processed by the morphophonology processor 214 or the mark-up processor 218, and thus these processors will not be utilized.

The syntax processor 210 is configured, in some example embodiments, to access an input, such as realization element data structure 230, and apply syntactic rules to generate natural language using a syntax rule file, such as a syntax rule file included in language rules file 240 a from a multilingual rules file 140. The syntax processor 210 is further configured, in conjunction with a multilingual rules file 140, to at least add closed class function words such as conjunctions (e.g. and, or), articles (a, the), demonstratives (this, that) and prepositions (to, from, at, with). In some embodiments, the syntax processor 210 is also configured, in conjunction with a multilingual rules file 140, to add morphological inflections. In some embodiments, the syntax processor 210 is also configured, in conjunction with a multilingual rules file 140, to at least propagate features in the realization element data structure 230. The operations and functionality of the syntax processor 210 is further described with regard to FIGS. 3, 5, and 6.

The morphology processor 212 of FIG. 2 is configured, in some embodiments, to receive an input from syntax processor 210, such as a syntactically updated realization element data structure 230, and to use at least one morphology rule file, such as a morphology rule file containing morphology rules, within a language rule file, such as language rules 240 a, comprising part of a multilingual rules file 140. The morphology rule file containing morphology rules is utilized in the language morphology processor 212 to generate a morphologically processed realization element data structure 230.

Morphology is accomplished by mapping base words forms into inflected word forms, by modifying the words of the element data structure into an inflected word form according to the language morphology rule file. By way of example, given an input “John, love, mango,” wherein mango includes the plural feature (i.e., mango[number:plural]), the morphology processor 212 is configured to output “John loves mangoes.” The morphing of love and mango from the base form to the inflected form is morphology. Alternatively or additionally, the morphology processor 212 may map inflected word forms to base word forms prior to mapping the base word forms to inflected word forms, to avoid errors in inflection.

In some examples, the morphology processor 212 is configured to mark the base word forms by the part of speech (pos) from which they come so that, for example, the noun date (day of the month or sweet edible fruit) is not confused with the verb date (assign a date to or meet a with a lover). In some examples, the correct part of speech may be taken from the input realization element. For example, love may be marked pos=verb. In this example, the morphology processor 212 is informed by the input realization element as to what base form it should identify, such as when searching multilingual lexicon 142.

In some example embodiments, the morphology processor 212 determines, for a particular word or phrase that is being processed, if the multilingual lexicon 142 records a non-standard inflected form (e.g., children as the plural of child). If so, the recorded form is used. If no recorded form is found, default morphology rules are used to form the inflected form (e.g., add “s” or “es” to form a plural, depending on the last letter of the base form, also change “y” to “i”). Alternatively or additionally, another example expression of the rules may include:

01. <rule conditions=“pos=verb tense=“past”>

02. <use>past</use>

03. <regex in=“y$” out=“ied”/>

04. <regex in=“e$” out=“ed”/>

05. <regex in=“$” out=“ed”/>

06. </rule>

In some examples, the morphology processor 212 is configured to receive a base word form and to access the lexicon, such as multilingual lexicon 142 to determine if it specifies the inflected form. If it does not, default morphology rules are applied as shown above. For example, in the case of arise the default output would be arised. However, the lexicon will override this default setting and specify arose.

In some examples, the morphophonology processor 214 is configured to receive an input, such as a processed realization element data structure 230, from morphology processor 212. In some examples, the morphophonology processor 214 may be configured to use at least one language morphophonology rule file, such as a morphophonology rule file containing morphophonology rules, within a language rule file, such as language rules 240 a, comprising part of a multilingual rules file 140, to generate a morphophonologically processed realization element data structure 230. For example, the morphophonology processor 214 may be configured to determine a prefix or indefinite article such as the English words “a” or “an.” This can be determined from a list of prefixes stored in memory. In some examples, the prefixes stored in memory specify that “an” should be used before any word that starts with the letters “um” (e.g., “an umbrella”) but “a” for any word starting with “uni” (e.g., “a university”). For example, when receiving a realization element data structure 230 at morphophonology processor 214 including the word components of the sentence “john attends an university”, the morphophonology processor will alter the “an” to “a”.

The orthography processor 216, in some examples, may be configured to receive an input, such as a processed realization element data structure 230, from the morphophonology processor 214, and to use at least one language orthography rule file, such as an orthography style file containing orthography rules, within a language rule file, such as language rules 240 a, comprising part of a multilingual rules file 140, to generate an orthographically processed realization element data structure 230. In some examples, the orthographically processed natural language is generated by capitalizing individual words or sentences by determining which words or sentences from the elements of the realization element data structure 230 to capitalize by comparing the elements of the realization element data structure 230 with the language orthography rule file, and then modifying the determined elements of the realization element data structure 230.

For example, the orthography processor 216 may be configured, in some examples, to input “john loves mangoes”. The orthography processor 216 determines from the input realization element data structure 230 and the orthography rules from the orthography rule file, the capitalization and punctuation operations and alters the realization element data structure 230 to the output “John loves mangoes.”. In some examples embodiments, capitalization of an input data structure can be controlled in several ways including leaving the capitalization as is, capitalizing the first letter of the first word in a sentence or clause, capitalizing the first letter of every word in a sentence or clause, capitalizing all words in a clause or sentence in upper case, or setting all words in a clause or sentence in lower case.

The mark-up processor 218 of FIG. 2, may be configured in some embodiments to use at least one language mark-up rule file to generate a marked-up realization element data structure 230 by converting internal markups found in realization element data structure 230 into a mark-up format or plurality of formats that can be understood by a plurality of natural language text presentation systems. In some examples, internal markups in the realization element data structure 230 can include bold font or red text. In some examples, the natural language text presentation systems can include HTML, Latex, or Word RTF.

FIG. 3 illustrates an example syntax processor 210. As outlined above, the syntax processor 210 is configured to access realization element data structure 230 and output syntactically processed realization element data structure 330. The realization element data structure 230 may take the form of a phrase specification output by a microplanner. That is, in some examples, the realization element data structure 230 is a syntactic representation of phrases and sentences received from a microplanner. In some examples, the realization element data structure 230 may be received from a lightweight NLG service invoked from a template.

The syntax processor 210 is configured to include a multilingual syntax processor 312 that is configured along with one or more language syntax processors 310 a, 310 b, and/or 310 c, to access and process the received realization element data structure according to a specific language. That is, language syntax processors 310 a, 310 b, and/or 310 c are configured to be operated by multilingual syntax processor 312 to syntactically process a realization element data structure 230 according to a specific language. While processors 310 a, 310 b, 310 c, and 312 are shown separately in FIG. 3, in some examples, they may be the same processor or may work in conjunction with each other on the same or shared processor.

The language syntax processors 310 a, 310 b, and/or 310 c are configured to access a syntax rule file, such as syntax rule file 340 a as part of a language rules file 240 a, comprising part of a multilingual rules file 140. In some examples, the syntax rule file, such as syntax rule file 340 a, may include rules for setting default features, adding closed class function words and morphological inflections, and/or propagating features. In some examples, rules for setting certain default language features, such as setting gender or tense to be used when processing the realization element data structure may be included in the syntax rule file 340 a.

In some examples, a language rules file that is input by the syntax processor 210 may include feature propagation rules. In some example embodiments, feature propagation may be included alongside default feature rules above in the syntax rule file 340 a which comprise part of a language rules file 240 a and multilingual rules file 140. In some examples, these default rules may be formatted to include the following English language example:

NounPhrase: noun.plural=specifier.plural [the plural value of an NP's noun is the same as the plural value of an NP's specifier]

NounPhrase: plural=noun.plural [the plural value of an NP as a whole is the same as the plural value of the NP's noun]

Clause: verb.plural=subject.plural [the plural value of a clause's verb is the same as the plural value of the clause's subject]

Clause: [if verb=BE] object.plural=verb.plural [the plural value of a clause's object is the same as the plural value of the clause's verb, if the verb is BE]

In some example embodiments, the syntax processor 210 may be configured to include one or more language specific syntax processors, such as language syntax processors 310 a, 310 b, and 310 c, and a multilingual syntax processor 312. The language specific syntax processors 310 a, 310 b, and 310 c are configured to build a syntax based on the syntax rule file received, such as syntax rule files 340 a, 340 b, and 340 c and/or perform language specific syntax functions. For example, language specific syntax functions may include adding closed-class functions words and morphological inflections and determining features. Closed class functions words include for example: conjunctions (e.g. and, or), articles (a, the), demonstratives (this, that) and prepositions (to, from, at, with).

In some embodiments, the syntax processor 210 is configured to access an unrealized realization element data structure 230 and output a syntactically processed realization element data structure 330. The realization element data structure 230 may be syntactic representations of phrases and sentences received from a microplanner. For example, an input data structure may include:

-   <Sentence tense=past negated=true> -   <NP role=subject>     -   <Noun word=“John”/>     -   </N P> -   <VP>     -   <Verb word=“buy”/>         -   <NP role=object>             -   <Number int=“100”/>             -   <Noun word=“share”/>         -   </N P>     -   <NP> -   </Sentence>     The output syntactically processed realization element data     structure is generated by the syntax realizer 210 by using the     language specific syntax processors, such as language syntax     processor 310 a, to perform language specific syntax operations and     the multilingual syntax processor, such as multilingual syntax     processor 312 to perform general syntax operations. The output is a     syntactically processed realization element data structure, which     may be outputted into the syntactically processed realization     element data structure 330. For example, the updated data structure     may include after the operation of the syntax processor: -   <Sentence tense=past negated=true>     -   <NP role=subject person=third number=singular>         -   <Noun word=“John” form=singular/>     -   </N P>     -   <VP person=third number=singular tense=past negated=true>         -   <Verb word=“do” form=simplePast/>         -   <Word word=“not” form=standard>         -   <Verb word=“buy” form=infinitive/>         -   <NP role=object number=plural>             -   <Number int=“100” form=standard/>             -   <Noun word=“share” form=plural/>         -   </N P>     -   <NP> -   </Sentence>

In some examples, the realization element data structure 230 may be syntactic representations of phrases and sentences received from sources other than the microplanner, such as a lightweight NLG service invoked from a template.

FIG. 4 is an example block diagram of an example computing device for practicing embodiments of an example lightweight multilingual realizer 134. In particular, FIG. 4 shows a computing system 400 that may be utilized to implement a natural language generation environment 100 having data analysis system 104 including in some examples a data analyzer 120 and a data interpreter 122. The natural language environment 100 also having a natural language generation system 108 including, in some examples, a document planner 130, a microplanner 132 and/or a lightweight multilingual realizer 134. One or more general purpose or special purpose computing systems/devices may be used to implement the natural language generation system 108. In addition, the computing system 400 may comprise one or more distinct computing systems/devices and may span distributed locations. In some example embodiments, the natural language generation system 108 may be configured to operate remotely via the network 450. In other example embodiments, a pre-processing module or other module that requires heavy computational load may be configured to perform that computational load and thus may be on a remote device or server. For example, the lightweight multilingual realizer 134 may be accessed remotely. Furthermore, each block shown may represent one or more such blocks as appropriate to a specific example embodiment. In some cases, one or more of the blocks may be combined with other blocks. Also, the natural language generation system 108 may be implemented in software, hardware, firmware, or in some combination to achieve the capabilities described herein.

In the example embodiment shown, computing system 400 comprises a computer memory (“memory”) 401, a display 402, one or more processors 403, input/output devices 404 (e.g., keyboard, mouse, CRT or LCD display, touch screen, gesture sensing device and/or the like), other computer-readable media 405, and communications interface 406. The processor 403 may, for example, be embodied as various means including one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits such as, for example, an application-specific integrated circuit (ASIC) or field-programmable gate array (FPGA), or some combination thereof. Accordingly, although illustrated in FIG. 4 as a single processor, in some embodiments the processor 403 comprises a plurality of processors. The plurality of processors may be in operative communication with each other and may be collectively configured to perform one or more functionalities of the lightweight multilingual realizer as described herein.

The natural language generation system 108 is shown residing in memory 401. The memory 401 may comprise, for example, transitory and/or non-transitory memory, such as volatile memory, non-volatile memory, or some combination thereof. Although illustrated in FIG. 4 as a single memory, the memory 401 may comprise a plurality of memories. The plurality of memories may be embodied on a single computing device or may be distributed across a plurality of computing devices collectively configured to function as the configurable microplanner system. In various example embodiments, the memory 401 may comprise, for example, a hard disk, random access memory, cache memory, flash memory, a compact disc read only memory (CD-ROM), digital versatile disc read only memory (DVD-ROM), an optical disc, circuitry configured to store information, or some combination thereof.

In other embodiments, some portion of the contents, some or all of the components of the natural language generation system 108 may be stored on and/or transmitted over the other computer-readable media 405. The components of the natural language generation system 108 preferably execute on one or more processors 403 and are configured to enable operation of a configurable lightweight multilingual realizer, as described herein.

Alternatively or additionally, other code or programs 430 (e.g., an administrative interface, a Web server, and the like) and potentially other data repositories, also reside in the memory 401, and preferably execute on one or more processors 403. Of note, one or more of the components in FIG. 4 may not be present in any specific implementation. For example, some embodiments may not provide other computer readable media 405 or a display 402.

The natural language generation system 108 is further configured to provide functions such as those described with reference to FIG. 1. The natural language generation system 108 may interact with the network 450, via the communications interface 406, with remote data sources 456 (e.g. remote reference data, remote lexicalization rules, remote aggregation data, remote genre parameters and/or the like), third-party content providers 454 and/or client devices 458. The network 450 may be any combination of media (e.g., twisted pair, coaxial, fiber optic, radio frequency), hardware (e.g., routers, switches, repeaters, transceivers), and protocols (e.g., TCP/IP, UDP, Ethernet, Wi-Fi, WiMAX, Bluetooth) that facilitate communication between remotely situated humans and/or devices. In some instance the network 450 may take the form of the internet or may be embodied by a cellular network such as an LTE based network. In this regard, the communications interface 406 may be capable of operating with one or more air interface standards, communication protocols, modulation types, access types, and/or the like. The client devices 458 include desktop computing systems, notebook computers, mobile phones, smart phones, personal digital assistants, tablets and/or the like.

In an example embodiment, components/modules of the natural language generation system 108 are implemented using standard programming techniques. For example, the natural language generation system 108 may be implemented as a “native” executable running on the processor 403, along with one or more static or dynamic libraries. In other embodiments, the natural language generation system 108 may be implemented as instructions processed by a virtual machine that executes as one of the other programs 430. In general, a range of programming languages known in the art may be employed for implementing such example embodiments, including representative implementations of various programming language paradigms, including but not limited to, object-oriented (e.g., Java, C++, C#, Visual Basic.NET, Smalltalk, and the like), functional (e.g., ML, Lisp, Scheme, and the like), procedural (e.g., C, Pascal, Ada, Modula, and the like), scripting (e.g., Perl, Ruby, Python, JavaScript, VBScript, and the like), and declarative (e.g., SQL, Prolog, and the like).

The embodiments described above may also use synchronous or asynchronous client-server computing techniques. Also, the various components may be implemented using more monolithic programming techniques, for example, as an executable running on a single processor computer system, or alternatively decomposed using a variety of structuring techniques, including but not limited to, multiprogramming, multithreading, client-server, or peer-to-peer, running on one or more computer systems each having one or more processors. Some embodiments may execute concurrently and asynchronously, and communicate using message passing techniques. Equivalent synchronous embodiments are also supported. Also, other functions could be implemented and/or performed by each component/module, and in different orders, and by different components/modules, yet still achieve the described functions.

In addition, programming interfaces to the data stored as part of the natural language generation system 108, such as by using one or more application programming interfaces can be made available by mechanisms such as through application programming interfaces (API) (e.g. C, C++, C#, and Java); libraries for accessing files, databases, or other data repositories; through scripting languages such as XML; or through Web servers, FTP servers, or other types of servers providing access to stored data. Alternatively or additionally, the input data 110, the multilingual rules file 140 and/or the multilingual lexicon 142 may be local data stores but may also be configured to access data from the remote data sources 456.

Different configurations and locations of programs and data are contemplated for use with techniques described herein. A variety of distributed computing techniques are appropriate for implementing the components of the illustrated embodiments in a distributed manner including but not limited to TCP/IP sockets, RPC, RMI, HTTP, Web Services (XML-RPC, JAX-RPC, SOAP, and the like). Other variations are possible. Also, other functionality could be provided by each component/module, or existing functionality could be distributed amongst the components/modules in different ways, yet still achieve the functions described herein.

Furthermore, in some embodiments, some or all of the components of the natural language generation system 108 may be implemented or provided in other manners, such as at least partially in firmware and/or hardware, including, but not limited to one or more ASICs, standard integrated circuits, controllers executing appropriate instructions, and including microcontrollers and/or embedded controllers, FPGAs, complex programmable logic devices (“CPLDs”), and the like. Some or all of the system components and/or data structures may also be stored as contents (e.g., as executable or other machine-readable software instructions or structured data) on a computer-readable medium so as to enable or configure the computer-readable medium and/or one or more associated computing systems or devices to execute or otherwise use or provide the contents to perform at least some of the described techniques. Some or all of the system components and data structures may also be stored as data signals (e.g., by being encoded as part of a carrier wave or included as part of an analog or digital propagated signal) on a variety of computer-readable transmission mediums, which are then transmitted, including across wireless-based and wired/cable-based mediums, and may take a variety of forms (e.g., as part of a single or multiplexed analog signal, or as multiple discrete digital packets or frames). Such computer program products may also take other forms in other embodiments. Accordingly, embodiments of this disclosure may be practiced with other computer system configurations.

FIGS. 5 and 6 illustrate example flowcharts of the operations performed by an apparatus, such as computing system 400 of FIG. 4, in accordance with example embodiments of the present invention. It will be understood that each block of the flowcharts, and combinations of blocks in the flowcharts, may be implemented by various means, such as hardware, firmware, one or more processors, circuitry and/or other devices associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory 401 of an apparatus employing an embodiment of the present invention and executed by a processor 403 in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowcharts' block(s). These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture, the execution of which implements the function specified in the flowcharts' block(s). The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowcharts' block(s). As such, the operations of FIGS. 5 and 6, when executed, convert a computer or processing circuitry into a particular machine configured to perform an example embodiment of the present invention. Accordingly, the operations of FIGS. 5 and 6 define an algorithm for configuring a computer or processor, to perform an example embodiment. In some cases, a general purpose computer may be provided with an instance of the processor which performs the algorithm of FIGS. 5 and 6 to transform the general purpose computer into a particular machine configured to perform an example embodiment.

Accordingly, blocks of the flowchart support combinations of means for performing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowcharts', and combinations of blocks in the flowchart, can be implemented by special purpose hardware-based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions.

In some example embodiments, certain ones of the operations herein may be modified or further amplified as described below. Moreover, in some embodiments additional optional operations may also be included. It should be appreciated that each of the modifications, optional additions or amplifications described herein may be included with the operations herein either alone or in combination with any others among the features described herein.

FIG. 5 is a flowchart illustrating an example method for generating natural language text at a syntax processor, such as by syntax processor 210, in a lightweight multilingual realizer, such as lightweight multilingual realizer 134. In block 502, at least one syntax rule file, such as syntax rule file 340 a, is received at a language syntax processor, such as language syntax processor 310 a. The syntax rule file 340 a may take the form of a general realizer language rule file including language rules for other realizer operations (e.g. morphology, orthography, etc. . . . ) or may be a syntax rule file that is separate from other rule files.

At block 504, at least one language lexicon, such as lexicon 242 a is accessed at a multilingual lexicon, such as multilingual lexicon 142. In some embodiments the language lexicon can be a language specific separate lexicon, while in other embodiments it may be a part of a multilingual lexicon.

At block 506, the natural language realizer accesses a realization element data structure, such as realization element data structure 230, wherein the realization element data structure is a syntactic representation of phrases and sentences. In some examples, the realization element data structure 230 may be received from a microplanner or may be received from a lightweight NLG service invoked from a template. In some examples, a realization element may define a phrase such as a noun phrase, verb phrase, and/or a prepositional phrase, among others. In some examples, a realization element may define a clause such as a sentence. In some examples, sentence clauses may have a noun phrase, a verb phrase, and an object or any many combinations of the phrases. For example, an input realization element data structure may take the form of:

-   <Sentence tense=past negated=true>     -   <NP role=subject>         -   <Noun word=“John”/>     -   </NP>     -   <VP>         -   <Verb word=“buy”/>         -   <NP role=object>             -   <Number int=“100”/>             -   <Noun word=“share”/>         -   </NP>     -   <NP> -   </Sentence>

At block 508, a syntax processor, such as syntax processor 210, accesses at least one syntax rule file, such as syntax rule file 340 a, and wherein the at least one syntax rule file is configured for a language. For example, syntax rule file 340 a may be configured to include rules for English language syntax processing, wherein the rules are a collection of rules to aid in the syntactic language operations performed by the syntax processor 210. Examples of components of syntax rules as part of a syntax rule file 340 a are described above in relation to FIG. 3.

At block 510, a syntax processor, such as syntax processor 210, is configured to add default and word-based features. For example, the syntax processor 210 may first propagate all explicitly specified features determined in the realization element data structure 230. The syntax processor 210 may then add default features when explicitly specified features are missing. For example, if syntax processor 210 determines a noun does not have a number feature set, the syntax processor will set the noun to the default feature, which is singular. In some examples, defaults from feature propagation, can be marked by the syntax processor 210 as “weak” values, which can be subsequently overridden during feature propagation. After adding default and word-based features, the example realization element data structure may take the form of:

-   <Sentence tense=past negated=true>     -   <NP role=subject>         -   <Noun word=“John” person=third number=singular/> lexicon             says John is third-person singular     -   </NP>     -   <VP>         -   <Verb word=“buy”/>         -   <NP role=object>             -   <Number int=“100” number=plural/> rules say 100 is                 plural             -   <Noun word=“share”/>         -   </N P>     -   <NP> -   </Sentence>

At block 512, a syntax processor, such as syntax processor 210, is configured to propagate features in the realization element data structure 230 by comparing one or more realization elements in the realization element data structure. Feature propagation and unification is one of the sub-tasks that is performed by the syntax processor 210 in the lightweight multilingual realizer 134. For example, given a realization element data structure 230, including a syntactic tree as input, the realization task is to unify and/or propagate certain syntactic features between different realization elements in the syntactic tree. For example, verifying that there is number agreement between the head noun in an object noun phrase (e.g. singular form of mangoes) with the head main verb (e.g. turning grow into grows). So as seen in some example embodiments, making sure mangoes grow and mango grows are paired together when necessary. After feature propagation, the example realization element data structure may take the form of:

-   <Sentence tense=past negated=true>     -   <NP role=subject person=third number=singular>         -   <Noun word=“John” person=third number=singular/>     -   </NP>     -   <VP person=third number=singular tense=past negated=true>         -   <Verb word=“buy” person=third number=singular tense=past             negated=true/>         -   <NP role=object number=plural>             -   <Number int=“100” number=plural/>             -   <Noun word=“share” number=plural/>         -   </N P>     -   <NP> -   </Sentence>

Alternatively or additionally, in some examples the syntax processor 210 may first propagate features as shown at block 512 and then, subsequently, add default words and features as shown in block 510.

At block 514, a syntax processor, such as syntax processor 210, is configured to add closed class function words and morphological inflections by utilizing rules from the syntax rule file 340 a. The syntax rule file 340 a is then used to determine closed class function words to add to the base words and phrases, and to determine the morphological inflections for the base words and phrases in the realization element data structure 230. Addition of closed class function words and morphological inflections is further described in detail in respect to FIG. 6. After insertion of function words and inflections, the example realization element data structure may take the form of:

-   <Sentence tense=past negated=true>     -   <NP role=subject person=third number=singular>         -   <Noun word=“John” form=singular/>     -   </N P>     -   <VP person=third number=singular tense=past negated=true>         -   <Verb word=“do” form=simplePast/>         -   <Word word=“not” form=standard>         -   <Verb word=“buy” form=infinitive/>         -   <NP role=object number=plural>             -   <Number int=“100” form=standard/>             -   <Noun word=“share” form=plural/>         -   </NP>     -   <NP> -   </Sentence>

At block 516, syntax processor 210 is configured to output the syntactically processed realization element data structure, such as syntactically processed realization element data structure 330. In some embodiments the output can be output directly to a user, or in some embodiments, the output can be further processed such as is shown in FIG. 2. For example, a syntactically processed realization element data structure may take the form of:

-   <Sentence tense=past negated=true>     -   <NP role=subject person=third number=singular>         -   <Noun word=“John” form=singular/>     -   </N P>     -   <VP person=third number=singular tense=past negated=true>         -   <Verb word=“do” form=simplePast/>         -   <Word word=“not” form=standard>         -   <Verb word=“buy” form=infinitive/>         -   <NP role=object number=plural>             -   <Number int=“100” form=standard/>             -   <Noun word=“share” form=plural/>         -   </N P>     -   <NP> -   </Sentence>

FIG. 6 is a flowchart illustrating an example method for adding closed class function words and morphological inflections. At block 602, a syntax processor, such as by syntax processor 210, is configured to access at least one syntax rule file, such as syntax rule file 340 a, wherein the at least one syntax rule file includes rewrite production rules for adding closed class function words and morphological inflections. In some examples, these rules are much simpler than syntactic rules in conventional realizers, since the rules are configured to assume that content words and constituents are mostly ordered. This in turn allows the rewrite production rule files to be smaller, more simple, and easier to write. In some examples, the rewrite production rules may include rules for forming verb groups such as:

-   Verb[passive:true *]→BE[*] Verb[inflection:pastParticiple] -   Verb[progessive:true *]→BE[*] Verb[inflection:presentParticiple] -   Verb[perfect:true *]→HAVE[*] Verb[inflection:pastParticiple] -   Verb[tense:future *]→WILL Verb[inflection:infinitive] -   <Start> BE[negated:true *]→BE[*] NOT -   <Start> Verb[negated:true *]<End>→DO[*] NOT     Verb[inflection:infinitive] -   <Start> Verb[negated:true *]→Verb[*] NOT -   Verb[tense:present *]→Verb[inflection:present *] -   Verb[tense:past*]→Verb[inflection:past *]

In this example, the rules are constructed so that the left hand side of the rewrite production rules divide “→” are syntactic features (such as tense and passive feature) used to determine the appropriate inflection or closed class function word. For example, left hand rules may include, but are not limited to:

-   Verb[ ]—can be used to specify any verb (including BE and HAVE). -   BE—matches verb BE. -   Verb[feature:value *]—matches any verb with this feature:value     pairs. “*” refers to remaining feature:value pairs. -   <Start> Verb—indicates the verb must occur at the start of the verb     group. -   <Start> Verb <End>—indicates the verb must occur at the start and     end of the verb group (i.e., it is the only word in the verb group).

Furthermore, in this example, the right hand side of the rule divide indicates the closed class function words and features to be added by the syntax processor 210. For example, right hand rules may include, but are not limited to:

-   Verb—indicates the same verb as on left hand side. -   Verb[feature:value]-indicates adding this feature:value to the verb. -   Verb [*]—indicates adding remaining feature value pairs from LHS. -   DO, NOT, BE, HAVE, WILL—indicates adding this function word.

At block 604, a syntax processor, such as by syntax processor 210, is configured to determine base words and phrases of the elements of the realization element data structure 230 to be modified by the addition of closed class function words, wherein the realization elements include determined features. For example, in the verb group rules described above, the syntax processor 210 is configured to identify the verbs and the determined features of the verbs using the left hand side of a rewrite rule of the set of rewrite rules.

At blocks 606-610 a syntax processor, such as by syntax processor 210, is configured to apply the rules for adding closed class function words and adding morphological inflections by processing the realization elements according to the determined features and corresponding closed class function word rule, by modifying the words and phrase and adding the determined closed class function words and morphological inflections. At decision block 606, a syntax processor, such as by syntax processor 210, is configured to determine if all applicable rules for adding closed class function words and morphological inflections have been applied. If there are rules that have not been applied, for example “No” not all rules have been applied, the syntax processor moves to block 608.

At block 608, a syntax processor, such as syntax processor 210, is configured to determine the first applicable rule for adding closed class function words and morphological inflections that has not been applied.

At block 610, a syntax processor, such as by syntax processor 210 is configured to apply the first applicable rule by processing the realization elements according to the determined features and corresponding closed class function word rule, by modifying the words and phrases and adding the determined closed class function words and morphological inflections.

In some examples, the iterations of blocks 606, 608, and 610 are demonstrated in relation to the verb group formation example described above, the iterations for an input realization element: “EAT[tense:past perfect:true negated:true]” may include:

Iteration 1:

Rule:

Verb[perfect:true *]→HAVE[*] Verb[inflection:pastParticiple]

Result:

HAVE[tense:past negated:true] EAT[inflection:pastParticiple]

Note: *matches features other than perfect:true, on EAT before the rewrite rule is applied; these are added to HAVE after the rewrite rule has been applied

Iteration 2

Rule:

<Start> Verb[negated:true *]→Verb[*] NOT

Result:

HAVE[tense:past] NOT EAT[inflection:pastParticiple]

Iteration 3

Rule:

<Start> Verb[tense: past *]→Verb[inflection:past *]

Result:

HAVE[inflection:past] NOT EAT[inflection:pastParticiple]

Iteration 4

Rule: No applicable rules found.

If at block 606, a syntax processor, such as by syntax processor 210, determines all applicable rules for adding closed class function words have been applied, then the process moves to “Yes” and block 612.

At block 612, a syntax processor, such as by syntax processor 210 is configured to return the realization element data structure for further use by a lightweight multilingual realizer. For example, in the above Iteration 4, the syntax processor 210 may determine no more applicable rules are found and returns the realization element data structure 230 for further use by the lightweight multilingual realizer 134.

In some embodiments, such as adding closed class functions for a verb group, the base words and phrases can include information such as: a head verb (e.g., “eat”), a particle (e.g., “up” in “eat up”), a modal word (e.g., “should” in “should eat”), and adverbs (e.g., “now” in “was now pursuing”). Forms and features (such as tense, negation, perfect tense, progressive tense, and number) are used to specify special verb group forms. Some examples of forms and features include:

Form: regular (e.g., I eat an apple)

-   -   Form: infinitive (e.g., “I want to eat an apple”)     -   Form: bare Infinitive (e.g., “I see John eat an apple”)     -   Form: gerund (e.g., “Eating apples is good for you”)

Tense: values are

-   -   Tense: past (e.g., “I ate an apple)     -   Tense: present (e.g., “I eat an apple)     -   Tense: future (e.g., “I will eat an apple)

Negated: values are

-   -   Negated: false (e.g., “I ate an apple”)     -   Negated: true (e.g., “I did not eat an apple”)

Perfect: values are

-   -   Perfect: false (e.g., “I ate an apple”)     -   Perfect: true (e.g., “I had eaten an apple”)

Progressive: values are

-   -   Progressive: false (e.g., “I ate an apple”)     -   Progressive: true (e.g., “I was eating an apple”)

Passive: values are

-   -   Passive: false (e.g., “I ate an apple”)     -   Passive: true (e.g., “An apple was eaten by me”)

Number: values are

-   -   Number: singular (e.g., “I was happy”)     -   Number: plural (e.g., “We were happy”).

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. 

That which is claimed:
 1. A method for generating syntactically correct natural language, the method comprising: accessing, using processing circuitry, a realization element data structure, wherein the realization element data structure is a syntactic representation of phrases and sentences; and accessing, using the processing circuitry, at least one syntax rule file at a syntax processor in a natural language realizer, wherein the at least one syntax rule file is configured for a language; generating, using the processing circuitry, a syntactically processed realization element data structure, at the syntax processor, using the at least one syntax rule file in the syntax processor by: propagating, using the processing circuitry, features in the realization element data structure by comparing one or more realization elements in the realization element data structure; adding, using the processing circuitry and to the realization element data structure, closed class function words and morphological inflections by utilizing rules from the syntax rule file to determine the closed class function words and morphological inflections to add to base words and phrases in the realization element data structure; and outputting, using the processing circuitry and for display via a computing device, natural language text generated based on the realization element data structure.
 2. The method of claim 1, wherein the syntax processor comprises one or more language specific syntax processors, which accesses and applies rules from the syntax rule file.
 3. The method of claim 1, wherein adding closed class function words and morphological inflections comprises: accessing, using the processing circuitry, rewrite production rules for adding closed class function words and morphological inflections in the at least one syntax rule file; determining, using the processing circuitry, base words and phrases of the elements of the realization element data structure to be modified by the addition of closed class function words and morphological inflections, wherein the realization elements include determined features; applying, using the processing circuitry, the rewrite production rules for adding close class function words and morphological inflections by iteratively processing the realization elements according to the determined features and corresponding closed class function word rule, by modifying the words and phrases and adding the determined closed class function words and morphological inflections; and determining, using the processing circuitry, if all applicable rules for adding closed class function words and morphological inflections have been applied and returning the realization element data structure for further use by the natural language realizer.
 4. The method of claim 1, wherein propagating features comprises: applying propagation and unification rules by: determining, using the processing circuitry, which words from the elements of the data structure to unify by comparing the elements of the data structure with rules for feature unification, and unifying, using the processing circuitry, features among the elements of the data structure by modifying the determined words according to the rules for feature unification.
 5. The method of claim 1, wherein the realization element data structure is received from either a microplanner or a lightweight NLG service invoked from a template.
 6. The method of claim 1, wherein the natural language realizer further optionally comprises a morphology processor, a morphophonology processor, an orthography processor, and a mark-up processor, and wherein the natural language realizer outputs fully realized natural language text.
 7. The method of claim 6, wherein the morphology processor, the morphophonology processor, the orthography processor, and the mark-up processor each comprise a language specific function processor, which accesses and applies rules from a language specific rule file.
 8. The method of claim 6, further comprising generating, using the processing circuitry, a processed realization element data structure, at the morphophonology processor, using the at least one language morphophonology rule file in the language morphophonology processor to generate a morphophonologically processed realization element data structure by: determining, using the processing circuitry, morphophonological features to modify the elements of the data structure according to the language morphophonology rule file; and applying, using the processing circuitry, the determined features to the realization elements.
 9. The method of claim 6, further comprising generating, using the processing circuitry, a processed realization element data structure, at the orthography processor, using the at least one language orthography style file in the language orthography processor to generate an orthographically processed realization element data structure by at least one of: capitalizing individual words; formatting numbers such as applying currency or date formats; performing punctuation operations; or placing white space characters between words.
 10. The method of claim 6, further comprising generating, using the processing circuitry, a processed realization element data structure, at the mark-up processor, using the at least one language mark-up rule file in the language mark-up processor to generate a marked-up realization element data structure by at least one of: converting internal markups found in the realization element data structure into a mark-up format or into a plurality of formats that can be understood by a plurality of natural language text presentation systems.
 11. The method of claim 1, wherein the natural language realizer receives language specific rule sets, wherein the language specific rule sets comprise: a syntax rule file, including at least rules to add closed class function words and morphological inflections, and propagate features; and optionally comprises any of: a language morphology rule file; a language morphophonology rule file; a language orthography style file; and a language mark-up rule file.
 12. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least: access a realization element data structure, wherein the realization element data structure is a syntactic representation of phrases and sentences; and access at least one syntax rule file at a syntax processor in a natural language realizer, wherein the at least one syntax rule file is configured for a language; generate a syntactically processed realization element data structure, at the syntax processor, using the at least one syntax rule file in the syntax processor by: propagating features in the realization element data structure by comparing one or more realization elements in the realization element data structure; adding closed class function words and morphological inflections to the realization element data structure by utilizing rules from the syntax rule file to determine closed class function words and morphological inflections to add to base words and phrases in the realization element data structure; and output, for display via a computing device, natural language text generated based on the realization element data structure.
 13. A computer program product comprising: at least one computer readable non-transitory memory medium having program code instructions stored thereon, the program code instructions which when executed by an apparatus cause the apparatus at least to: access a realization element data structure, wherein the realization element data structure is a syntactic representation of phrases and sentences; and access at least one syntax rule file at a syntax processor in a natural language realizer, wherein the at least one syntax rule file is configured for a language; generate a syntactically processed realization element data structure, at the syntax processor, using the at least one syntax rule file in the syntax processor by: propagating features in the realization element data structure by comparing one or more realization elements in the realization element data structure; adding closed class function words and morphological inflections to the realization element data structure by utilizing rules from the syntax rule file to determine the closed class function words and morphological inflections to add to base words and phrases in the realization element data structure; and output, for display via a computing device, natural language text generated based on the realization element data structure. 